The door of an automotive vehicle typically consists of an inner panel and an outer panel, both made of a resilient metal such as steel. The panels are preliminarily held together by overlapping flanges along the edges and then welded together at a welding station where the door is retained in a fixed position by several clamps.
It is essential that the door be held correctly without bending or flexing the panels, so that the geometry of the door is right for welding. Otherwise, when released after welding, the door may spring-back to a slightly warped condition. This may prevent the door, when installed in a vehicle, from sealing properly against the frame, producing wind noise, water leaks and an unsightly appearance. To eliminate the problem, the clamps used to hold the door during welding, or at least some of the clamps, must be adjusted. In the past, it has been necessary to make the adjustment manually by shimming the clamps. The operator made this adjustment based on his experience and judgment. This was very time-consuming and subject to error.